TM
55-6680-234-40
q. Connect unit to vacuum pump model 25
of 88 to 92 percent nitrogen with the bal-
ance helium. Gas mixture must be at least 98
Hyper Vac; evacuate to a pressure of 50 mi-
percent pure, free from dust particles, and it
crons or less; with vacuum maintained, bake
must contain not more than 0.006 milligram
unit at 160 10 degrees for 8 hours. Backfill
indicator to a pressure of approximately one
per liter (dew point -65 degrees C) of water
vapor.
atmosphere with a gaseous mixture composed
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